The role of infrared thermal imager in fire protection
In large areas of forest, fires are often caused by invisible hidden fires. This is the root cause of devastating fires, and it is difficult to find such hidden fire signs with the existing common methods. However, patrolling with an airplane and using an infrared thermal imager can quickly and effectively detect these hidden fires and eliminate them in the first place. The Canadian Forestry Institute began conducting forest fire tests as early as 1975. From the aircraft, it checked the potential fire sources of the unburned ground. The Canadian Forest Research Center used helicopters to use the AGA750 portable thermal imager and found 15 hidden fires in a fire season. fire. Grain silos tend to spontaneously ignite. This spontaneously ignited phenomenon often takes a long time, comes vigorously, and suffers large losses. At present, a thermometer is generally used to measure the temperature change of the granary to prevent it. Using a thermal imager can accurately determine the location and scope of these fires, so that we can know and prevent them as soon as possible. Using a thermal imager is convenient, simple, fast, and timely extinguished.
Infrared cameras can also be used to detect poor contact with electrical equipment and overheated mechanical parts to avoid serious short circuits and fires.
In the four years from 1980 to 1983, China conducted overheating inspections on more than 10,000 plugs in 20 power plants, 8 substations, and 24 high-voltage lines in the North China Electric Power Network using self-made thermal imaging cameras, and found more than 500 abnormal heating points The location was severely overheated at 100 locations. Due to timely treatment, there was no fire accident.
Abroad, the statistics of American insurance companies indicate that more than 25% of all electrical equipment hidden dangers are the main cause of fires, which are caused by poor plug contact. Therefore, the National Fire Protection Association ’s "Electrical Maintenance Manual 70B" provides After any electrical plug is tightened according to the specified torque, as long as this torque value does not change, it should not be tightened again in the future. Therefore, the well-made and properly installed electrical plug does not need to be tightened regularly. Only when it is found to be abnormal and overheated, it must be dealt with.
For all directly visible devices, infrared thermal imaging products can determine the thermal hazards of all connection points. For those parts that cannot be directly seen due to the shielding, you can find out the heat hazards according to the heat conduction to the external components. This is the traditional method. Except for the physical examination and cleaning the joints, There is no other way. Infrared thermal imaging products cannot replace circuit breakers, conductors, bus bars and other components for operational testing. However, infrared thermal imaging products can easily detect circuit overload or three-phase load imbalance.
MAI Corporation of the United States has conducted infrared thermal imaging product inspections on many general electrical preventive equipment and found that many of the equipment that has undergone maintenance still have electrical failures. For example, an important manufacturer of electronic products, this company carries out power outage maintenance for its electrical equipment every two years. During this power failure operation, the equipment is cleaned, all connection points are tightened and the circuit breaker is tripped. And test the installation of high and low voltage switchgear. Infrared thermal imaging product inspections performed after traditional repairs still identified some hidden dangers. There were 19 severe hidden cases found on different devices, and generally 179 hidden cases. These serious hidden dangers refer to the surface temperature of the tested equipment exceeding the maximum design temperature of NEMA or UL. Most of the hidden troubles were found on the motor control equipment, and some hidden troubles were also found on the switch gear and power disk. Another example is the preventive maintenance of equipment every six months after a fire in a major motor control center in a federal government office building. After the fire, two repairs were carried out, and another infrared thermal imaging product inspection was conducted. The result was: 3 before the serious repair and preventive repair, and 3 after the preventive repair. So the necessity of infrared thermal imaging product inspection is obvious.
In addition, using infrared thermal imaging products instead of traditional methods of cleaning and fastening can save a lot of money. There are two reasons for this savings: First, the inspection of infrared thermal imaging products is very fast, and unlike the traditional method, it takes a lot of manpower to clean and fasten the equipment. In addition, when the infrared thermal imaging product inspection is in progress, the equipment is not required to be powered off, but only after finding out the hidden troubles, it is required to be powered off for a short time when performing repairs. And the power outage for repairing individual hidden dangers is only partial, the power outage time is very limited, and it may even be scheduled to be repaired within the planned power outage time. Here are a few examples.
1), an "asset management company" in the United States implements a complete maintenance project that includes all motor control equipment, lighting, power panels and switching devices (excluding circuit breaker trip tests). The fee is based on the workload. The average maintenance cost of a typical office building (250,000 square feet, 10 floors) is $ 6,500. Infrared thermal imaging product inspection in the same building can complete the inspection of all motor controls, switchboards and switchgears (including various mechanical equipment) in just one day. The infrared thermal imaging product inspection service fee is about US $ 600 to US $ 800 . Therefore, the cost of infrared thermal imaging products is only 1/10 of the cost of traditional methods.
2) Before signing the infrared thermal imaging product inspection contract, an "Electronic Equipment Manufacturing Plant" uses a four-day power outage, and three groups of five electricians perform traditional maintenance. Workers work 12 hours a day to clean and tighten Connection points in all switching devices, motor control equipment and power panels. The labor cost for these jobs is US $ 30,000. The inspection of infrared thermal imaging products of the same equipment was also carried out for 4 days, and was completed with the assistance of two factory workers. The cost was only US $ 3,000.
3), a large-scale "office / hotel / sales commercial complex" carries out traditional maintenance of high and low switching devices every three years, and the cost of cleaning and fastening work during the maintenance period is at least US $ 20,000. The inspection of infrared thermal imaging products on the same equipment took only 12 hours and cost only 2,000 US dollars. 12 hidden dangers were found, two of which were serious hidden fire hazards.
4) Through the inspection and analysis of infrared thermal imaging products, the annual cost of a "small American factory" will be reduced from 160 to 40 man-hours. For example, according to the cost of 25 USD / hour (including overtime), the annual savings of 120 hours, that is, 3000 USD can be saved.
According to the above experience of the United States, replacing the regular cleaning and fastening work in traditional maintenance with infrared thermal imaging product inspection can save costs by 50% -90%, and can effectively prevent the occurrence of fire. For example, during July-August 1985, the Washington Post described the fire, personal injury, property damage, and production and tax losses caused by these accidents on the front page based on many electrical equipment power outages that occur almost every day. . For example, a power outage at a local hotel caused a loss of $ 6.5 million. To avoid the power outages mentioned above, many commercial and industrial organizations often spend a lot of money performing preventive maintenance work. Unfortunately, these tasks not only often fail to discover the existing hidden dangers, but also may cause new electrical hidden dangers. Therefore, the inspection of infrared thermal imaging products of electrical equipment can replace traditional preventive maintenance in many ways.
The United States Bulletin No. 375 of "Equipment Operation and Production Control Technology" states that both new and old buildings can benefit from the inspection of infrared thermal imaging products. Nearly 50 companies in the United States provide infrared thermal imaging product inspection services for all electrical equipment and power distribution systems of customers, including high-voltage contactors, fuse panels, main power circuit breaker panels, contactors, and all distribution lines, Infrared thermal imaging inspection of motors, transformers, etc., to ensure that all electrical equipment of the customer does not have latent thermal hazards, and effectively prevent the occurrence of fire. Statistics from American insurance companies have also shown that inspection of infrared thermal imaging products on all electrical equipment can greatly reduce unsafe factors and save a lot of insurance expenses. Below are some facilities that require inspection of infrared thermal imaging products.
1), Various electrical devices: Potential problems such as loose or poor contact, unbalanced load, overload, overheating, etc. can be found. The potential impact of these hidden dangers is arcing, short circuit, burnout, and fire. Their average repair cost is 10,000 to 50,000 US dollars; replacement requires 80,000 to 100,000 US dollars, and the construction period is a few weeks to several months.
2) Transformer: Hidden joints that can be found are loose joints, overheated casing, poor contact (tap converter), overload, unbalanced three-phase load, and blocked cooling pipes. Its effects are arcing, short circuit, burnout, and fire. Rewinding costs 10,000 to 50,000 US dollars, to replace 80,000-140,000 US dollars, the construction period is a few weeks or months.
3), Motor, generator: The hidden dangers that can be found are excessive bearing temperature, unbalanced load, short-circuit or open circuit of the winding, carbon brush, slip ring and collector ring heating, overload and overheating, cooling pipe blockage. The effect is that the faulty bearing can cause damage to the iron core or the winding ring, and the faulty carbon brush can damage the slip ring and the current collecting ring, and thus damage the winding coil. It may also cause damage to the drive target. The motor rewinding coil (5000 horsepower) needs 50,000 to 100,000 US dollars, and replacement requires 100,000 to 200,000 US dollars. The construction period is a few weeks to several months.
4), electrical equipment maintenance inspection, roof leak detection, energy saving inspection, environmental protection inspection, security and theft prevention, forest fire prevention, nondestructive testing, quality control, medical inspection, etc. are also very effective.
In addition, there is also an example of using thermal imaging for electrical equipment charge inspection in Beijing: before the new embassy of the Canadian Embassy in China was commissioned, a company in Hong Kong was commissioned in September 1992 to use thermal imaging equipment produced in the The internal electrical equipment was subjected to a comprehensive inspection of fire and thermal hazards, and a thermal imaging inspection service fee of USD 4,000 was paid. In fact, the preparation time is not calculated, and the actual time for inspection is only one day.
Similarly, infrared thermal imaging products are also very useful in the investigation of fire and explosion accidents. Infrared thermal imaging has become more and more important in the legal affairs of fire and other accidents, especially around the complex technical issues related to loss of life or property. Losses caused by fires and explosions often involve thermal hazards, thermal propagation, etc., and these conditions can be quickly observed and recorded with infrared thermal imaging products, so infrared thermal imaging is a strong visual evidence that can make non- Professionals are also clear at a glance, and can make fair decisions and trials of losses. The following are several examples of the use of infrared thermal imaging in the investigation of fire and explosion accidents.
Local governments and insurance companies in the United States often require analysis of the causes of personal and property losses. Corresponding investigations may not find criminal acts, such as murder or arson. But the investigation can discover the equipment failure and damage status, and how to avoid these problems in the future. Thermal images on burnt buildings often enable people to understand the real situation of how a fire or explosion occurs. And experimentally reproduce the process of fire, explosion or equipment damage to supplement the understanding of the incident. Infrared thermal imaging provides a very good visual means to analyze and reproduce accidents caused by heat. Infrared and video recordings of experimental fires, explosions, and equipment damage enable people to have a deeper understanding of their causes.
In the United States, explosions cause millions of dollars in property damage each year. When detecting experts investigate and analyze these events and determine the possible causes, they often use the method of recurring events to understand the explosion mechanism. For example, using infrared thermal imaging products to take a set of photos to show the explosion occurred in a car, used to simulate an accident caused by terrorists or arsonists. In these infrared thermal images, white represents heat and black represents cold. It is used to artificially reproduce the explosion phenomenon, analyze the accident, and determine the type and cause of the accident. Here are a few examples.
1) In a test car, a one-gallon barrel of gasoline was placed on the driver's seat, and a pound of explosive was placed under it. The explosive was detonated remotely by electronic instruments. Infrared thermal imaging video can record the test vehicle at about 0.04 seconds after the explosion, showing the fireball emitted from gasoline, the range of radiation emitted after the accident, and the development of the subsequent explosion. This heat profile, which can only be obtained by infrared thermal imaging, shows the range of heat conduction during and after explosion. It is easy to identify the projectile trajectories of explosive debris by replaying thermal image recordings, and these trajectories are often not found when replaying visible light recordings. The thermal image left on the exterior of the vehicle can indicate the high temperature distribution area, which is often used as a clue to find the source of the accident.
2) Another similar test is to use abandoned houses as the test target. In this test, 0.25 pounds of C4 explosive was placed under a can of one gallon of gasoline. The results show the initial state of the test house, the initial thermal state and a series of subsequent situations, including the thermal state 3 seconds after the explosion, the residual heat emitted by the explosion and its initial cause of ignition, and further expansion after a few minutes Can be seen for fire.
The procedure for analyzing the cause and source of fire in the United States is similar to the analysis of explosion accidents. The identification of thermal images can help people determine the cause of fire and provide information on the cause of the accident for detailed inspection of the fire point. Here are a few examples.
1) For example, infrared thermal imaging video can show the process of fire in a car. Acetone and polystyrene are mixed together to form a spherical plastic mass, which is located near the steering rod in the engine room and is ignited. Infrared thermal imaging video can show the fire after about 3 minutes, the local heating in the protective glass window is obvious. It can also show that hot gas enters the passenger compartment through the fire wall, and the higher radiation emitted from the windows confirms this situation. In addition, infrared thermal imaging video shows the volatile gas leaking from the engine room, showing the process of volatile liquid leakage and combustion. In addition, the infrared thermal image recording can also show that the flame in the fire zone is extinguishing. The thermal image can clearly describe the various stages of the fire process, and it is being used in the training of fire investigators.
2) Infrared thermal imaging video of a fire test in an abandoned house can show that a firefighter is placing the igniting liquid mixture and shaking the chloride powder stored in a cabinet, and the subsequent development of the fire. The hot air flow formed from top to bottom, as can be seen from these infrared thermal imaging videos, the speed of heat conduction from the fire point in the cabinet is very fast.
3) Fires and explosions caused by mechanical or electrical equipment manufacturing problems are often concerned by investigators. For example, in a house, a fire caused by a heater failure caused a person to die from smoke. When inspecting a floor-standing heater, as long as it is exactly the same as the heater that caused the fire, the thermal image of the heater during operation can be obtained, you can see the hot test point (hottest) on the thermal image at the high temperature limit Near the switch, it was determined that the fault was caused by the copper wire, which was enough to ignite the debris and powder inside the heater, and the bottom box to protect the high limit switch. The high-temperature bright spot seen on the thermal image exceeds the temperature rating of the wire insulation. In this environment, the aging of the wire will inevitably lead to a short circuit and cause a fire. The thermal image not only provides a quantitative temperature value, but also provides an obvious and intuitive description of the way the fault occurs.
4) An overheated belt traction wheel, this belt traction wheel tries to drive a blocked compressor. The question answered from this test is how high the temperature between the V-belt and the belt traction wheel can ignite the flammable gas near this equipment. A flammable gas with a ignition temperature of 6000 F was ignited, and a nearby compressor exploded, causing serious damage to the oil processing plant and casualties. The temperature is measured at the outer edge of the wheel using the infrared thermal image, and the obtained information is used as the boundary condition of the finite element heat conduction analysis. The calculation results show that the temperature between the fan belt traction wheel and the belt exceeds 8000 F. This temperature is to ignite flammable gases, which are leaked from the oil processing plant equipment of the factory due to negligence.
5) After the fire, American investigators collected evidence from witnesses, fire departments, police and the scene. In situations where mechanical or electrical equipment may cause a fire, infrared thermal imaging data obtained from past energy calculations or equipment analysis may be useful. For example, a thermal image of an air hander with an overheated motor and fan belt traction wheels. The heat emitted from the belt and the belt traction wheel quickly passed through the metal casing on the outside of the device. In the future, if it is suspected that this air transmission device may cause a fire, the infrared thermal image of the device that is almost damaged can be an important basis for explaining the cause of the fire.
Deluxe Rice Cooker was one of electric type rice cooker , but it`s the most popular type of electric rice cooker . especially famous in Southeast Asia area with its good appearances with various functions. Not only its outer shell could be customized with different demands, but also it speeding cooking , saving times and electricity, enhancing our lifestyle
Features
The inner pot is made of solid and durable aluminum alloy of high intensity , such as non-stick inner pot , stainless steel inner pot and honeycomb patterned inner pot with non-stick coating.
There are some models that use stainless steel instead of aluminium .Various other materials, such as copper, pure carbon, ceramic, and diamond powder coating, may be used for higher heat conductivity or better taste.
Applications
Multifunction , can cooking rice, soup and much more. added cooking versatility with supplied steam tray.
Some rice cookers have settings for congee, a type of rice porridge called okayu in Japanese, Juk in Korea, and zhou in Chinese.
More elaborate recipes are possible using a rice cooker, and there are cookbooks devoted entirely to dishes prepared using a rice cooker. It is possible to cook soups, stews or sponge cakes in electric rice cookers. By simply adding ingredients and setting it to "warm", a rice cooker cooks the contents at about 65 °C (150 °F). In a few hours, the stew is fully cooked and ready to eat.
Deluxe Rice Cooker
Deluxe Rice Cooker,Cylinder Rice Cooker,Mini Rice Cooker,Stainless Steel Rice Cooker
Guangzhou Taipeng Electrical Appliances Technology CO., LTD. , https://www.kettles.pl